The present disclosure generally relates to a method of improving Seismic data by reducing the effects of multiple reflected energy. Seismic exploration involves surveying subterranean geological formations for hydrocarbon deposits. A survey typically involves deploying seismic source(s) and seismic sensors at substantially predetermined locations. The sources generate seismic waves which propagate into the geological formations creating pressure changes and vibrations along their way. Changes in elastic properties of the geological formation scatter the seismic waves, changing the properties of the seismic waves. For example, the direction of propagation of the seismic wave may be altered. Part of the energy emitted by the sources are reflected from interfaces between subterranean formations. Some of the reflected waves reach the seismic sensors, which detect seismic waves. There are various types of seismic sensors. Some are sensitive to pressure changes (hydrophones) and others are sensitive to particle motion (geophones). Industrial surveys may deploy either one type of sensor or both types. In response to the detected waves, the sensors generate electrical signals to produce seismic data. Analysis of the seismic data (or traces), the shape, position, and composition of the subterranean formations can be determined and can then be indicative of the presence or lack thereof of probable locations of hydrocarbon deposits
Some surveys are known as “marine” surveys because they are conducted in marine environments. However, “marine” surveys may be conducted not only in saltwater environments, but also in fresh and brackish waters. In a first type of marine survey called a “towed-array” survey, an array of streamers and sources is towed behind a survey vessel. In a second type of marine survey, an array of seismic cables, each of which includes multiple sensors, laid on the ocean floor, or sea bottom; and a source is towed behind a survey vessel.
Oftentimes, seismic waves reflect from interfaces other than just those between subterranean formation, as would be desired. Seismic waves sometimes reflect from the water bottom and the water surface, and the resulting reflected waves themselves continue to generate further reflections. Waves that reflect multiple times are referred to as multiple reflections or “multiples”. Surface multiples are those waves that have reflected multiple times between the water surface and any upward reflectors, such as the water bottom or formation interfaces, before being senses by a receiver. Generally, surface multiples are considered undesirable noises that interfere with and complicate the desired data.
Considerable effort is expended in the design of seismic data acquisition and the processing of seismic data to limit the effect of multiple reflections on seismic data. Nevertheless, in many instances, present methods of processing seismic data are not as efficient as they could be. Accordingly, a need exists for an efficient method for attenuating seismic data multiples.